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Cancer gene therapy is first to be approved

28 November 2003

By Sylvia Pagán Westphal

For the first time, a gene therapy-based treatment has been given the go-ahead by regulatory authorities. China’s medicines authority approved the cancer therapy after it achieved promising results in a clinical trial.

The treatment, called Gendicine, will be launched commercially in January by SiBiono GeneTech of Shenzhen, Guangdong province. The results of the trial will be published in December in China’s national medical journal, says Zhaohui Peng, the company’s founder and head, and he plans to translate the paper into English to submit to an international journal.

Gendicine’s approval was announced over a month ago but has gone largely unnoticed outside China. Most gene therapy experts contacted by New Scientist knew nothing about it.

But French Anderson of the University of Southern California, a renowned gene therapy pioneer, visited SiBiono earlier in 2003 and also met the head of the Chinese drug approval agency. “The Chinese did evaluate this in considerable detail, so this was not a trivial approval,” he says. “This was a serious in-depth analysis.”

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Run amok

The treatment consists of an adenovirus designed to insert a gene called p53. This gene codes for a protein that triggers cell suicide when cells start to run amok, preventing them becoming cancerous.

Many tumours arise after the mutation or inactivation of p53, and in cancers of this type restoring the protein should kill the tumour cells. This approach has already been tried in the US, with mixed results.

SiBiono decided to test the treatment on head and neck squamous cancers, as p53 is known to be mutated in over 60 per cent of these tumours. This form of cancer is also particularly common in China.

In the largest clinical trial, 120 patients with nasopharyngeal cancer were given either radiotherapy alone, or Gendicine and radiotherapy. The p53-carrying viruses were injected directly into tumours once a week for eight weeks, and most patients were monitored for more than a year afterwards.

In 64 per cent of patients given Gendicine there was complete regression of primary tumours, a rate three times as great as that in the radiotherapy-only group. Peng hopes the virus will work against other kinds of cancers too.

Simple is better

The only side effect, he says, was fever in around a third of patients. He does not expect any long-term adverse effects because the virus does not integrate into the genome of cells – unlike the viruses used in the French gene therapy trial halted in 2002 after two boys developed leukaemia.

Anderson, who has agreed to become an unpaid adviser to SiBiono, says the company’s adenovirus is relatively simple compared with the gene-delivery systems being developed in the west. “But sometimes simple is better,” he says.

A dose will cost just 3000 yuan (&dollar;360), Peng told New Scientist, and can easily be administered by any doctor.

The development has been hailed in China as another sign of how the country is forging ahead in scientific research. However, the approval of Gendicine is also likely to provoke criticism from western researchers who think it is too early to bring gene therapy to patients, especially after such a small trial.

With 300,000 new cases of head and neck squamous cancers each year, China clearly thinks the benefits outweigh the risks. If Gendicine proves successful, SiBiono plans to launch the therapy in south-east Asia before seeking approval elsewhere.